.main-bg {
    background-image: url('../images/bg-mb.png');
    background-size: cover;
    padding-bottom: 60px;
}
@media screen and (min-width: 640px) {
    .main-bg {
        background-image: url('../images/bg-pc.png');
    }
}
.post-title{
    line-height: 1.3;
    text-align: center;
}
.post-img{
    margin-top: 30px;
}
@media screen and (min-width: 640px) {
    .post-img{
        margin: 30px auto 0;
        width: 60%;
    }
}
.post-sub-content{
    padding: 40px 0 30px;
}
.post-sub-content:nth-child(even){
    background-color: #a5a5a57a;
}
.post-sub-title{
    margin: 0 0 30px;
    font-size: 22px;
    text-align: center;
    color: #0d6575;
}
.post-sub-description{
    letter-spacing: 3px;
    line-height: 1.7;
}